Automated test equipment utilizes its channels to drive signals to or receive signals from a device under test (DUT). Each device under test is typically comprised of address PINs, control PINs, and data PINs. In the past, the automated test equipment has used dedicated PIN electronics channels for the data PINS. As a result, there was a one-to-one relationship between the channels and the data PINs on a device under test. In other words, the PIN electronics channels for the data lines were not shared by multiple devices under test. As a result, the time needed to test multiple devices—for example on a wafer—was long due to the fact that data for each device under test had to be read serially.
While attempts have been made to utilize the same PIN electronics channel to read data from multiple devices under test, they have required that the data be read serially from these devices under test. Thus, a first data read has to be performed from the first device under test, followed by a data read on the second device under test, followed by a third data read from the third device under test, etc. Thus, the time to perform data reads from multiple devices in this serial fashion has increased the testing time by a factor of the number of devices being tested. For example, to read from four devices under test utilizing the same test channel requires four times as long as it would be required to read data from a single device under test. As a result, the test time overhead (TTO) has typically been unacceptable. Thus, testing has typically been performed by dedicating a single PIN IO channel of a testing device to an individual data PIN on a device under test.
Another drawback in the past to testing multiple devices has been the lack of electrical isolation between devices in performing data reads from the devices. Thus, when two devices, for example, are read in a serial manner using a single data line, a bad device under test can unnecessarily cause the other device under test to appear damaged or of low quality. For example, if a first device under test has an electrical short, the lack of electrical isolation when reading from the second device under test can cause a second device under test to perform poorly. As a result, the second device under test might be categorized as substandard.